Data compression techniques aim to optimize storage and transmission of data by removing redundant information. Lossless compression methods like Run-Length Encoding and Huffman Coding replace repetitive patterns with codes to reduce file size without losing any original data. Lossy methods like JPEG, MPEG, and MP3 are commonly used for images, video, and audio as they allow for smaller file sizes by discarding imperceptible data. These methods break files into blocks, apply transforms to reveal redundancies, then quantize and encode the data.